A peer-to-peer (P2P) network allows wireless devices to directly communicate with each other. Wireless devices within range of each other can discover and communicate directly without involving central access points.
An “ad hoc network” refers to a self-configuring network of nodes connected by wireless links which form an arbitrary topology. An ad hoc network typically includes a number of geographically-distributed, potentially mobile units, sometimes referred to as “nodes,” which are wirelessly connected to each other by one or more links (e.g., radio frequency communication channels). The nodes can communicate with each other over a wireless media without the support of an infrastructure-based or wired network. Links or connections between these nodes can change dynamically in an arbitrary manner as existing nodes move within the ad hoc network, as new nodes join or enter the ad hoc network, or as existing nodes leave or exit the ad hoc network. One characteristic of the nodes is that each node can directly communicate over a short range with nodes which are a single “hop” away. Such nodes are sometimes referred to as “neighbor nodes.” A large network can be realized using intelligent access points (IAP) which provide wireless nodes with access to a wired backhaul.
A wireless mesh network is a collection of wireless nodes or devices organized in a decentralized manner to provide range extension by allowing nodes to be reached across multiple hops. In a multi-hop network, communication packets sent by a source node can be relayed through one or more intermediary nodes before reaching a destination node. When a node transmits packets to a destination node and the nodes are separated by more than one hop (e.g., the distance between two nodes exceeds the radio transmission range of the nodes, or a physical barrier is present between the nodes), the packets can be relayed via intermediate nodes (“multi-hopping”) until the packets reach the destination node. In such situations, each intermediate node routes the packets (e.g., data and control information) to the next node along the route, until the packets reach their final destination. For relaying packets to the next node, each node maintains routing information collected through communication with neighboring nodes. The routing information can also be periodically broadcast in the network to reflect the current network topology. Alternatively, to reduce the amount of information transmitted for maintaining accurate routing information, the network nodes may exchange routing information only when it is needed.
Recent developments within various Institute of Electrical and Electronics Engineers (IEEE) 802 standards have considered support for the International Telecommunication Union's (ITU's) International Mobile Telecommunications (IMT) Advanced requirements. (for IEEE standards referenced herein, see, http://standards.ieee.org/getieee802/index.html or contact the IEEE at IEEE, 445 Hoes Lane, PO Box 1331, Piscataway, N.J. 08855-1331, USA)
International Mobile Telecommunications-Advanced (IMT-Advanced) is a concept from the ITU for mobile communication systems with capabilities which go further than that of the current system requirements. In the vision of the ITU, there may be a need for a new wireless access technology capable of supporting a wide range of data rates according to economic and service demands in multi-user environments with target peak data rates of up to approximately 100 Mega bits per second (Mbit/s) for high mobility such as mobile access and up to approximately 1 Giga bits per second (Gbit/s) for low mobility such as nomadic/local wireless access.
Spectrum considerations for IMT-Advanced include up to 100 Mega Hertz (MHz) of bandwidth in either licensed or unlicensed spectrum below 6 Giga Hertz (GHz). The IMT-Advanced Network Topology requirement proposes multi-hop, mesh and P2P (peer-to-peer) modes. As such, the IEEE 802.16m operational requirements call for multi-hop relay support as well as self-optimization of network performance with respect to service availability, quality of service (QoS), network efficiency and throughput.
In an ad hoc network topology supporting direct link and multi-hop mesh, several challenges exist to enable peer-to-peer (P2P) communication sessions to support use cases such as out-of-coverage range extension, in-building penetration, social networking, gaming, public safety, and short range communication for high density environments or infrastructure off-loading. These challenges include efficient resource allocations, synchronization, route discovery, and near-far interference. In a system design employing an Orthogonal Frequency Division Multiple Access (OFDMA) Physical Layer (PHY) (such as IEEE 802.16e), an additional challenge is multi-access interference resulting from synchronization errors. With the current IEEE 802.16e frame structure, it is not possible to enable in-band and out-of-band multi-hop relays for peer-to-peer communications unless these challenges are resolved.
Accordingly, there is a need for system for enabling mobile coverage extension and peer-to-peer communications in an ad hoc network.
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